U.S. patent number 4,380,721 [Application Number 06/221,085] was granted by the patent office on 1983-04-19 for proximity switch.
Invention is credited to John W. Bullock, Lawrence T. Miranda.
United States Patent |
4,380,721 |
Bullock , et al. |
April 19, 1983 |
Proximity switch
Abstract
A proximity switch or detector is disclosed herein having an
oscillator circuit for establishing a radio frequency field about
an antenna so that the presence of an object or agent in close
proximity to the antenna causes the oscillator to become loaded and
to cease oscillations. A voltage comparator senses a change of
voltage from the oscillator and triggers a bistable circuit. A
power-up or setting circuit primes the bistable circuit to be
responsive to the trigger signal from the voltage comparator which,
in turn, actuates an output driver circuit incorporating a light
emitting diode network operably coupled to a load plug
interconnecting with a suitable electrical appliance intended to be
actuated by the presence of the object or agent.
Inventors: |
Bullock; John W. (Camarillo,
CA), Miranda; Lawrence T. (Ewa Beach, HI) |
Family
ID: |
22826275 |
Appl.
No.: |
06/221,085 |
Filed: |
December 29, 1980 |
Current U.S.
Class: |
315/362; 315/150;
315/76 |
Current CPC
Class: |
H03K
17/9547 (20130101); H03K 17/951 (20130101) |
Current International
Class: |
H03K
17/94 (20060101); H03K 17/95 (20060101); H05B
037/02 (); H01K 007/00 () |
Field of
Search: |
;331/65 ;315/362,76,150
;361/181 ;340/552 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dixon; Harold A.
Attorney, Agent or Firm: Marrs; Roger A.
Claims
What is claimed is:
1. A proximity switch for sensing the presence of an object or
agent comprising the combination of:
an antenna;
an oscillator coupled to said antenna and adapted to modify
oscillations in response to the presence of an object or agent in
close proximity to said antenna;
a voltage comparator operably coupled to said oscillator for
initiating a trigger signal in response to modification of
oscillations from said oscillator;
a voltage setting circuit producing a threshold voltage level;
a bistable circuit operatively coupled to said voltage setting
circuit and responsive to said trigger signal in the presence of
said threshold voltage level to provide an output voltage
level;
a load operably connected to said bistable circuit for receiving
said output voltage level and being actuated thereby;
a feedback circuit connected between said antenna and said
oscillator;
an amplifier circuit interconnecting said oscillator circuit with
said feedback circuit for rectifying its output;
an output driver network including a light emitting diode circuit
operably coupled between said load and said bistable circuit;
said voltage setting circuit is a first flip-flop circuit and said
bistable circuit is a gate circuit having a second flip-flop
circuit;
an inductive load compensator network coupled to said load;
said voltage comparator is coupled to said oscillator circuit via
said amplifier circuit for sensing a dip in voltage therefrom
resulting from the inference with an electromagnetic field
surrounding said antenna; and
said electromagnetic field is established by said oscillator.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to proximity switches or detectors
and more particularly to electronic controlled devices of this type
sensitive to the presence of a person or object in its
vicinity.
2. Brief Description of the Prior Art
In the past, a variety of proximity detectors and switches have
been employed which respond to the presence of an object or agent.
Problems and difficulties have been encountered with these prior
devices such as disclosed in U.S. Pat. Nos. 3,384,789 and 2,810,066
which stem largely from the fact that mechanical relys are
employed. Such relys are noisy and have a tendancy to foul easily.
Also, these latter devices are electro-mechanical and are therefore
heavy and require mechanical maintenance.
Therefore, a long standing need has existed to provide a novel
proximity detector or switch which is composed entirely of
electronic components and which is not sensitive to spurious line
voltages or other interferences.
SUMMARY OF THE INVENTION
Accordingly, the above problems and difficulties are obviated by
the present invention which provides a novel proximity detector or
switch having an oscillator means for establishing an
electromagnetic field about an antenna such that the presence of an
object or agent in the field causes the oscillator to be loaded to
the point where oscillations cease so as to provide a variable
voltage output. Amplifier means are connected to the oscillator
means for monitoring the condition of the oscillator means and for
rectifing its output. A voltage comparator circuit is operably
connected to the amplifier means for sensing the dip in voltage
resulting from the interference with the electromagnetic field so
as to produce a signal in response thereto. An output circuit
including a bistable device is connected to the voltage comparator
circuit in order to receive the signal generated thereby and to
pass the signal in combination with a voltage level from a setting
circuit for operably actuating an output driver circuit connected
to a load.
Therefore, it is among the primary object of the present invention
to provide a novel proximity detector or switch having improved
switching means for controlling energation of a variety of
electrical appliances.
Another object of the present invention is to provide a novel
proximity switch which includes bistable elements as a switch
operable in response to voltage levels from a voltage comparator
circuit as well as a setting circuit for operably powering a load
comprising a variety of suitable electronic appliances for
apparatus.
Still a further object of the present invention is to provide a
novel proximity switch which is totally electronic in operation and
in construction and which is void of mechanical relys, switches or
the like.
Still a further object of the present invention is to provide a
novel electronically controlled proximity switch or detector
wherein the sensitive element is operable by the presence of a
person or object within a predetermined distance therefrom and one
which will differentiate between certain objects and others such as
being sensitive to the proximity of a human being, but which is
unaffected by an inanimate object such as a plant.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention which are believed to be
novel are set forth with particularity in the appended claims. The
present invention, both as to its organization and manner of
operation, together with further objects and advantages thereof,
may best be understood by reference to the following description,
taken in connection with the accompanying drawings in which:
FIG. 1 is a prospective view of a lamp constituting a purely
illustrative embodiment of the present invention and which
incorporates the proximity switch of the present invention mounted
on the underside of a supporting table;
FIG. 2 is a block diagram illustrating the general circuit of the
present invention; and
FIG. 3 is a detailed schmetic drawing of the proximity switch
incorporating the present invention showing the various components
therefore.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, an exemplary electric lamp is shown in the
general direction of arrow 10 which includes a base 11 supporting
an upright rod 12 terminating in a typical electrical socket
carrying a light bulb 13. The light bulb is surrounded by a
suitable shade 14 and the lamp 10 is supported on the upper surface
of a table 15. The novel proximity detector or switch of the
present invention is indicated by numeral 16 and is located out of
visual sight by placement underneath the table top 15. Any suitable
means for installation may be used. The lamp 10 is electrically
connected to the proximity detector 16 via a conventional cord and
plug indicated by numeral 17. In broken lines 18, an area is
suggested in which the proximity detector will function when an
intruder or object, such as wand 20, is waved.
Referring now to FIG. 2, a block diagram is illustrated showing the
circuit arrangement comprising the electronic embodiment of the
proximity detector 16. Within the detector, there is provided an
antenna 21 for radiating an electromagnetic, radio frequency field
which is indicated by numeral 18 in FIG. 1. An oscillator circuit
22 establishes the R F field around the antenna 21. The output of
the oscillator circuit is coupled to an amplifing circuit 23 which
monitors the condition of the oscillator and rectifies the output
voltage therefrom and further, isolates the oscillator circuit from
the remainder of the components. A feedback circuit 24
automatically adjusts the oscillator so that a constant voltage is
present at the output of the amplifier 23 when there is no
interference or disruption of the field 18. The output condition of
the oscillator circuit when at constant voltage may be referred to
as an idle condition.
A voltage comparative circuit 25 monitors the output D C Voltage of
the amplifier 23. When the voltage reaches a predetermined
threshold or level, a trigger signal is released and applied to a
gate output circuit 26. The gate output circuit comprises a
bistable flip flop which is set to an "off" condition by a power-up
or setting circuit 27. The setting circuit 27 is operated when the
power supply 28 is initially plugged into line voltage. In other
words, when power is applied to the setting circuit 27, the flip
flop power-up circuit prevents the gate output circuit 26 from
going to a random "on" condition. This always assures that the
output from the gate output 26 will be in the "off" condition when
the power is turned "on" until the trigger pulse is received from
the voltage comparator circuit 25.
When the voltage from the amplifier circuit reaches a predetermined
level at the voltage comparator circuit 25, a trigger signal is
introduced to the gate output circuit 26. As mentioned earlier,
this output stage will react to the trigger signal only when the
power-up or setting circuit is satisfied that the applied voltage
is stablized which is evidenced by the gate circuit being in the
"on" condition. If the above conditions are met, the gate output
circuit will flip to an "on" condition. Upon receiving the next
trigger signal, the gate output circuit will go to the "off"
condition. In other words, when the voltage comparator circuit is
in the non-idle condition, a variable voltage is produced by the
interference with the R F field so that the voltage comparative
circuit senses a dip in voltage at the antenna which tunes the
antenna coil to the oscillator coil so that the coil is loaded
permitting current to flow. The voltage comparator circuit senses
the change in voltage and initiates a trigger signal to the gate
output circuit which is turned "on" since it is in the "off"
condition in response to the setting circuit 27.
The output of the gate output circuit 26 is introduced to an output
driver circuit 30 which isolates the 120 volt AC from the rest of
the low voltage circuit. The input to the output driver circuit is
amplified and through an optial-electric technique, such as use of
a light emitting diode, a triac is turned "on". Operation of the
triac applies power to a load indicated by numeral 31. An induced
load compensator 32 is employed to stabilize the load when
energized.
Referring now to FIG. 3, the circuit details of the present
invention is illustrated and it can be seen that the block diagram
of FIG. 2 is superimposed over the components and elements of the
circuit and identified by corresponding reference numerals. It is
noted that the oscillator circuit is a standard circuit employing
transistors 40 and 41 which are operably connected to a tank
circuit indicated in general by numeral 42. The tank circuit is
connected to the antenna 21. Whenever an object, such as a persons
hand, passes over the antenna 21, that is within approximately zero
to six inches therefrom, the oscillator will become loaded to the
point where oscillations cease. It is at this time that the voltage
comparator 25 takes action and produces a trigger signal. The
amplifier 23 is of conventional construction employing a transistor
43 and an integrated circuit 44. The comparator 25 includes an
integrated circuit 45 which is directly coupled to one half of an
integrated circuit 46 which is a standard dual flip-flop circuit.
The integrated circuit 46 is identified as a Model 4013 and the
other half of the flip-flop is identified by numeral 47 which is in
the power-up or setting circuit 27. A pair of triacs 48 and 49 are
included in the output driver 30 and are identified in the industry
as M C 3011 and may be obtained from the Motorola. These triacs are
of the optical variety. Through optical electronic techniques, the
light from the light emitting diode 50 causes the triac to turn
"on". There is no electrical circuit between the light emitting
diode and the triac. The isolation voltage between the light
emitting diode and the triac is seventy five hundred volts peak AC
for five seconds.
The integrated circuit in the comparator 25 as indicated by numeral
45 is an industry standard identified by the numerals LM 311 while
the operational amplifier 44 is identified as an industry standard
by UA 741. The power supply 28 employs a standard bridge circuit 51
while a plug 52 connects with suitable line voltage. An output plug
53 may be readily attached to any suitable appliance or load such
as the lamp shown in FIG. 1. An inductive load compensator 32 is
provided by the series connection of capacitor 54 and resistor
55.
Therefore, in view of the foregoing it can be seen that the novel
circuit of the present invention provides a novel proximity switch
which may be readily activated by the presence of an object or
agent in the vicinity of the antenna 21. The circuit is maintained
in tune so as to compensate for the growth of nearby plants or the
like. The circuit operates only in the presence of rapidly moving
objects or persons. The power supply 28 is plugged into a normal
120 volts, AC house current and changes the line voltage to a low
voltage DC, which is used to service all the internal circuits. The
oscillator circuit 22 sets up a radio frequency field around the
antenna 21 while the amplifier circuit monitors the condition of
the oscillator, rectifies its output and isolates the oscillator
from the rest of the circuit. The feedback circuit automatically
adjusts the oscillator so that a constant voltage is seen at the
output of the amplifier.
When the power is applied by plugging in to the line voltage, the
flip-flop in the power-up or setting circuit 27 maintains the gate
output flip-flop from going to a random "on" condition. It always
assures that the output will be in the "off" position when power is
applied. The voltage comparator 25 monitors the output DC voltage
of the amplifier. When the voltage reaches a predetermined level, a
trigger signal is initiated to the gate output flip-flop 26. If the
above conditions are met, the output circuit will go to an "on"
condition. Upon receiving the next trigger signal, the output
circuit 30 will go to the "off".
In other words, when the voltage from the amplifier circuit is
constant, this represents an idle condition. When the output from
the amplifier circuit is a variable voltage, then interference with
the RF about the antenna 21 is present. The voltage comparator
circuit senses a dip in the voltage at the antenna which tunes out
the oscillator coil so that the coil is loaded and current will
flow. Zero voltage is represented by the idle condition. The
voltage comparator senses the voltage and fires a flip-flop to
actuate the gate output circuit.
The output driver 30 isolates the 120 volt AC voltage from the rest
of the low voltage circuit. The input to the output driver is
amplified and the signal drives the light emitting diode. Through
opto-electronic techniques, the light from the light emitting diode
causes the triac to turn "on". There is no electrical circuit
between the light emitting diode and the triac.
A high resistance to high voltage is shown which is able to get
back into the circuit itself so that no dangerous potential or
voltage will be available or present at the antenna. However,
further isolation is provided by enclosing the antenna and making
it inaccessible for touching or handling.
Whenever an object, such as the hand or the body of a person passes
in close proximity to the antenna 21, the oscillator will become
loaded to the point where oscillations cease. It is at this time
that the voltage comparator takes action and produces a trigger
signal. The feedback circuit is employed to slowly adjust for
changes in the close environment such as humidity, nearby growing
plants or any change near the antenna.
While particular embodiments of the present invention have been
shown and described, it will be obvious to those skilled in the art
that changes and modifications may be made without departing from
this invention in its broader aspects and, therefore, the aim in
the appended claims is to cover all such changes and modifications
as fall within the true spirit and scope of this invention.
* * * * *